Industrial robots are commonly used in various industries due to their flexibility. However, their adoption for machining tasks is minimal because of the low dynamic stiffness characteristic of serial kinematic chains. To overcome this problem, we propose coupling two industrial robots at the flanges to form a parallel kinematic machining system. Although parallel kinematic chains are inherently stiffer, one possible disadvantage of the proposed system is that it is heavily overactuated. We perform a modal analysis to show that this may be an advantage, as the redundant degrees of freedom can be used to shift the natural frequencies by applying tension to the coupling module. To demonstrate the validity of our approach, we perform a milling experiment using our coupled system. An external measurement system is used to show that tensioning the coupling module causes a deformation of the system. We further show that this deformation is static over the tool path and can be compensated for.

翻译：工业机器人因其灵活性而广泛应用于各行各业。然而，由于串联运动链的低动态刚度特性，其在机械加工任务中的应用十分有限。为解决这一问题，我们提出将两台工业机器人的法兰端耦合，构成并联运动加工系统。尽管并联运动链具有更高的固有刚度，但所提系统的一个潜在缺陷是存在严重过驱动问题。通过模态分析表明，冗余自由度可通过向耦合模块施加张力来改变系统固有频率，这恰恰可能转化为优势。为验证该方法的有效性，我们采用耦合系统进行了铣削实验。利用外部测量系统证明，对耦合模块施加张力会导致系统产生变形，并进一步证实该变形在刀具路径上保持静态特性，可通过补偿予以消除。